Frank l



Patented Aug. 15, 1950 1- DICARBALKOXYMETHYLENE 2 ALKYL- 1,2-DIHYDROISOQUINOLINES AND METH- OD OF PRODUCING THEM Frank L. White and Leslie G. s. Brooker, Rochester, N. Y., assignors to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey "No Drawing. Application April 19, 1946,

Serial No. 663,620

esters, and that the resulting 1.-dicarbalkoxymethylene-2a1kyl-I,2'-dihydroisoquinolines can be hydrolyzed to give l-methylisoquinoline alkyl quaternary salts in substantial ields.

' It is, accordingly, an object of our invention to provide 1-dicarbalkoxymethylene-2-alkyl-1,2- dihydroisoquinolines and a process for preparing the same. A further object is to provide a process for" preparing l-lnethylisoquinoline alkyl quaternary salts. Other. objects will become apparent hereinafter. I

In accordance with our invention we prepare 1 dicarbalkoxymethylene 2 alkyl- 1,2 dihydroisoquinolines which can be represented the following general formula:

wherein 13,31 and Ba each, represent an alkyl group, i. e. an alcohol radical. e. g. a methyl, an ethyl, an n-propyl, an n-butyl, an iso-butyl, .an allyl, .a ,B-methoxyethyl, a s-hydroxyethyl, a. B-acetoxyethyl, a Bacetylthyl, a benzyl, a p-phenylethyl group, etc., by condensing a 1-alkylmercaptoisoquinoline alkyl quaternary salt which can berepresented by-the following general formula: V

wherein R has the values given above, R representsjan alkyl group, i. e. analcohol'radica-I such 12 Claims. (01. 260-287) as set forth above under Formula I, and X represents an .anion, e. g. chloride, bromide, iodide, methylsulfate, ethylsulfate, p-toluenesulfonate, benzenesulfonate, acetate, perchlorate, thiocyanate, etc., with a malonic ester which can be represented by the following general formula:

III. 000R;

wherein R1 and R2 have the values given above. Advantageously compoundsof Formulas I, II and III are employed wherein the alkyl groups are primary alkyl groups of the formula CnH2n+1 wherein n represents a positive integer of from 1 to 4.

The condensations are advantageously effected in the presence of an acid-binding agent (basic condensing agent) which is advantageously a tertiary organic amine, e. g. trimethylamine, triethylamine, triisopropylamine, tri-n-propylamine, "triisobutylamine, tri-n-butylamine, triethanolamine, tripropanolamine, N-rnethylpiperidine, N-ethylpiperidine, i. e. a tertiary organic amine whichhas an ionization constant greater than 10- at 25 C.

Advantageously the-condensations are effected in a diluent. Alcohols which are liquid at 20 C. are advantageously employed as the diluent, especially alcohols of the formula CnH2n+1OH wherein n represents a positive integer of from 1 to 4. Heat accelerates the condensations.

The following example will serve to illustrate further the manner of obtaining l-dicarbalkoxymethylene-Z-alkyl-1,2-dihydroisoquinolines:

Example 1.-1-dicarbethom/methylene-Z-methyl- 1,2-dz'hydroisoquz'noline L [/COOCzHs N oooozn5 A mixture of. 14.55 g. (1 mol.) of Z-methyl- 1.(2)thioisoquinoline and 15.5 g. (1 mol.) of methyl-p-toluenesulfonate were heated together at the temperature of the steam bath for-(3 hours. To the resulting 1.-methylthioisoquinoline methop-toluenesulfonate were added 19.95 g. (1 mo1.+50% excess) of diethyl malonate, 35 cc. of ethyl alcohol and 8.83 g. (1 mol.+5% excess) of triethylamine. The resulting mixture was heated at the refluxing temperature for 30 minutes. The. cooled reaction mixture was then stirred with 250 cctof diethyl ether. The ether mixture was chilled overnight at 0 C., and the 59 i??- Whitih was present was then collected on a filter and washed with diethyl ether. The washed solid was then stirred, in a beaker, with hot methyl acetate. ture was chilled at C., and the solid washed onto a filter with methyl acetate. 1 (dicarbethoxymethylene) 2 methyl 1,2 dihydroisoquinoline at this point was 59% and can be used without further'purification. A portion of the product was twice recrystallized from a mixture of equal volumes of ethyl alcohol and methyl acetate, and gave orange crystals, melting at 189-191 C. with decomposition;

In the same manner 1-dicarbethoxymethylene-- Z-ethyl-1,2-dihydroisoquinoline can be prepared by using 15.2 g. of 2-ethyl-1(2) -thioisoquinolone instead of 14.55 g. of 2-methyl-l(2) -thioisoquinolone; 1-dicarbethoxymethylene-2-n-propyl- 1,2-dihydroisoquinolone can be prepared using 16.9 g. of 2-n-propyl-1(2) -thioisoquinolone; 1- dicarbethoxymethylene-Z- isobutyl 1,2-dihydroisoquinoline can be prepared using 18 g. of 2- isobuty1-1(2) -thioisoquinolone; l-dicarbethoxymethylene-2-benzyl-1,2-dihydroisoquinoline can be prepared using 18.7 g. of 2-benzyl-1(2) thioisoquinolone; 1-dicarbethoxymethylene-2 allyl- LZ-dihydroisoquinoline can be prepared using 16.7 g. ,of 2-allyl-1(2)-thioisoquinolone; l-dicar-bethoxymethlylene-2-/3-hydroxyethyl- 1,2 dihydroisoquinoline can be prepared using 1'7 g. of Z-B-hydroxyethyl-MZ)-thioisoquinoline, etc. 1-dicarbmethoxymethylene-Z methyl-1,2 dihy droisoquinoline can be prepared, employing 16.3 g. of dimethylmalonate instead of 19.95 g. of diethyl malonate; 1-dicarbpropo-xymethylene-2- methyl-1,Z-dihydroisoquinoline can be prepared using 23.5 g. of di-n-propylmalonate; l-dicarbisobutyroxymethylene-2-methyl-1,2-dihydroisoquinoline can be prepared using 2'7 g. of diisobutylmalonate, etc.

The 2-methyl-1(2) -thioisoquinolone employed in the foregoing example can be prepared as shown in the following example:

Example 2.2-methyZ-1(2) -thioisoquinolone fl r f.

A mixture of 31.8 g. (1 mol.). of 2-methyl-1(2)- isoquinolone and 44.4 g. (1 mol.) of phosphorous pentasulfide in '75 cc. of pyridine was heated at the refluxing temperature for one hour. The reaction mixture was chilled and stirred with 500 cc. of cold water and then allowed to stand overnight at 0 C. The solid material was then collected on a filter and washed with cold water. The washed solid, while still moist, was extracted with two portions of boiling ligroin (B. P. 90 to 120 C.), 400 cc. and 240 cc. respectively. The 2-methyl-1(2) -thioisoquinolone which separated from each of the cooled extracts was filtered OE, and then recrystallized from ligroin (B. P. 90 to 120 C.) again to give cream colored crystals, melting at 113 to 115 C. In like manner 2-ethyl-1(2)-thioisoquinolone was prepared from 2-ethyl-1(2) -isoquinolone. The brownish crystals recrystallized from ligroin melted at 114 to 115 C. and after washing with acetone became cream colored and melted at 118 to 119 C.

In the same manner 2-n-propyl-M2.) Qi Q- The methyl acetate mix-.

The yield of quinoline can be prepared'using 37.4 g. of 2-nprcpyl-1(2)-isoquinolone instead l of 31.8 g. of 2-methyl-1(2) isoquinolone; 2-isobutyl 1(2) thioisoquinolone can be prepared using 40.2 g. of 2-iso-butyl-1(2)-isoquinolone; 2-allyl-1(2)- thioisoquinolinecan be prepared using 37 g. of 2-allyl-1(2)' isoquinolone; 2 p hydroxyethyl- 1(2) -thioisoquinolone can be prepared using 37.8 g. of p-hydroxyethyl 1(2) isoquinolone; 2- benzyl-1(2)-thioisoquinolone can be prepared using 47 g. of 2-benzyl-1(2) -isoquinolone, etc.

The 2 methyl-1(2)-isoquinolone employed in the foregoing example is described by Fisher and I-Iamer; J. Chem. Soc. 1934, 1905. It can be prepared as shown in the following example:

Example 3.2-methyZ-1 (2) -is0'quinolone 129 g. (1 mol.) of freshly distilled isoquinoline warmed on a steam bath, and 186 g. (1 mol.) of methyl-p-toluenesulfonate were added gradually with shaking. After addition of the methylp-toluenesulfonate, the mixture was heated for one hour. The resulting quaternary salt was dissolved in water, and-the solution was chilled in an ice-water bath. 724 g. (2 mols. +10% excess) of potassium ferricyanide were dissolved in 2 l. of warm water and a solution of 264 g. (4 mols.) of potassium hydroxide in cc. of water wereadded to the ferricyanide solution. After chilling the potassium-hydroxideferricyanide solution to about 10 0., the cold aqueous solution of the quaternary salt was added gradually to the potassium-hydroxide-ferricyanide solution, with mechanical stirring, and continued cooling, so that thetemperature of the reaction mixture did not rise above about 12 C. The reaction mixture was then stirred for about one hour, and it was then left standing at about 0 C. for a further hour. The 2-methyl- 1(2) -isoquinolone was extracted from the reaction mixture with benzene. The benzene extract \vas'washed with water and the benzene removed by distillation at atmospheric pressure. The residue was distilled at reducedv pressure whereupon 67 g. of 2-methyl-1(2) -isoquinolone boiling at 194 to 200 C. at 25 mm. of Hg pressure were obtained.

In like manner 2-ethyl-1(2) -isoquinolone was prepared from 283 g. of crude isoquinoline ethoethylsulfate. The yield of 2-ethyl-1(2) -isoquinolone, boiling at 180 to C. at 20 mm. of Hg pressure, was 80g. Similarly 2-n-propyl- 1(2) -isoquinolone can be 1 prepared from isoquinoline n-propom toluenesulfcnate; 2-n-butyl- 1(2)-isoquinolone from isoquinoline n-buto-ptoluenesulfonate; 2-al1yl-1 2) -isoquinoline can be prepared from isoquinoline alliodide; 2-fl-hydroxyethyl-1'(2) -isoquinolo ne can be prepared from isoquinoline [i-hydroxyethobromide; 2- benzyl-1(2)'-isoquinolone can be prepared from isoquinoline benzobromide; etc. The isoquinoline alko-p-toluenesulfonates or alko-alkylsulfates are advantageously. employed where available, because of their greater water solubility..

In Example 1, 2-methyl-1(2) -thioisoquinolone can be converted into a l-alkylmercaptoisoquinoline alkyl quaternary salt by heating with ethyl, n-propyl or n butyl-p-toluenesulfonate instead of methyl-p-toluenesulfonate. Likewise ethyl, n-propyland n-butyl-p-toluenesulfonate can be heated with any of the aforesaid 2-alkyl- 1( )-thioisoquino1ones to give l-alkylmercaptoisoquinoline alkyl quaternary salts. Similarly the 2-alkyl-1(2)-thioisoquinolones can be heated with dimethyl sulfate, diethyl-sulfate, allyl bromide,.n-propyl iodide, benzyl bromide, fl-methoxyethyl bromide, S-hydroxyethyl bromide, etc. to give 1-alkylmercaptoisoquinoline alkyl quaternary salts. The 1-alkylmercaptoisoquinoline alkyl quaternary iodides can be converted to perchlorates by treating a hot methyl alcoholic solution of the iodide with a hot aqueous solution of sodium perchlorate, and to the acetates by heating a methyl alcoholic suspension of the iodide with silver acetate, filtering of the silver salts and separating the alkyl quaternary acetate from the resulting solution. I

The 1 dicarbalkoxymethylene-2-alkyl-1,2-dihydroisoquinolines of our invention can be hydrolyzed to give excellent yields of 1-methylisoquinoline alkyl quaternary salts. The hydrolysis is carried out in the presence of an acid, advantageously hydrochloric acid, hydrobromic acid, sulfuric acid or phosphoric acid. Heat accelerates the hydrolysis. The more water-soluble 1- methylisoquinoline alkyl quaternary salts obtained in accordance with our invention, e. g. the l-methylisoquinoline alkochlorides, can be converted, into less soluble quaternary salts by treating'an aqueous or alcoholic solution of the 1- methylisoquinoline alkochlorides with an aqueous or alcoholic solution of an alkali metal (e. g. sodium or potassium) perchlorate, iodide, etc.

.The following examples will serve to illustrate further the manner of obtaining l-methylisoquinoline alkyl quaternary salts by means of our new process:

Example 4.-i-methylisoqui1toline methiodide A mixture of 28.4 g. of l-dicarbethoxymethylene-Z-methyl-1,2-dihydroisoquinoline and 1500 cc. of concentrated hydrochloric acid (sp. g. 1.12)

' was heated over a free flame at such a rate that carbon dioxide was evolved freely. The flame was increased and near the end of the evolution of carbon dioxide, the mixture was heated at the I ,hot' filtrate (about 270 cc.) was chilled at C'.

The l-methylisoquinoline methiodide which separated was filtered off and washed with acetone. The cream colored crystals weighed 22 grand were; further purified by recrystallizing from ethyl alcohol.

" Example 5.--Z-mcthylz"soquinoline ethiodide A mixture of 18.9 g. (1 mol.) of 2-ethyl-1(2)- thioisoquinolone and 20 g. (1 mol.) of ethyl-ptoluenesulfonate were heated together at the temperature of the steam bath for 24 hours. To this crude quaternary salt were added 24 g. (1

mol.+ 50% excess) of diethyl malonate, 50 cc.

of ethyl alcohol and 10.6 g. (1 mol.-|-% excess) of triethylamine, and the reaction mixture was heated at the refluxing temperature for 30 minutes.

6. The reaction mixture was concentrated on the steam bath, under reduced pressure, until no more'distillate came over. The residue of 1- dicarbethoxymethylene 2 ethyl-1,2-dihydroisoquinoline was dissolved in 100cc. of concentrated hydrochloric acid (sp. g. 1.12), and this solution was heated over a free flame at such a rate that carbon dioxide was evolved freely. The flame was increased and near the end of the evolution of carbon dioxide, the mixture was refluxed. The total time of heating was 90 minutes. The mixture was then evaporated to dryness, under reduced pressure, and the residue of l-methylisoquinoline methochloride was dissolved in hot ethyl alcohol, and a hot solution of 15 g. of sodium iodide in ethyl alcohol was added. The hot suspension was filtered to remove sodium chloride and the sodium chloride on the filter was washed with ethyl alcohol. The combined filtrate and washings were chilled to 0 C. and the l-methylisoquinoline ethiodide which separated was collected on a filter and washed with acetone. The acetone-washed product was extracted with hot ethyl alcohol and the extract was concentrated to 220 cc. and then chilled to 0 C. The cream colored crystals which separated weighed 13 g. and melted at 215 to 216 C.

In a similar manner l-methylisoquinoline npropiodide can be prepared from l-dicarbethoxymethylene-Z-n-propyl 1,2-dihydroisoquinoline; l-methylisoquinoline n-butiodide can be prepared from 1-dicarbethoxymethylene-2-n-butyl- 1,2-dihydroisoquinoline; l-methylisoquinoline hydroxyethiodide can be prepared from l-dicarbethoxymethylene 2-;3-hydroxyethyl 1,2 dihydroisoquinoline; l-methylisoquinoline benziodide can be prepared from l-diearbethoxymethylene- 2-benzy1-1,2-dihydroisoquinoline, etc.

The l-methylisoquinoline alkyl quaternary salts obtainable by our new process can be condensed with cyclammonium quaternary salts containing a S-arylaminovinyl group to give carbocyanine dyes, and with other substances to give other kinds of methine dyes. See our copending application Serial No. 663,619, filed of even date.

herewith.

What we claim as our invention and desire to be secured by Letters Patent of the United States 1. The 1-dicarbalkoxymethylene-Z-ialkyl-1,2- dihydroisoquinolines which are represented by a the following general formula:

| COORz R cooal L L N C\ I COORz R wherein R, Bi and R2 each represents a'pi'iniary alkyl group of the formula CnH2n+1 wherein n represents a positive integer of from 1 t 4;:

3. 1 dicarbethoxymethylene- 2 methyl-1,2 dihydroisoquinoline having the following :formula: 9

H3 v 4. 1 dicarbethoxymethylene 2; ethyl 1,2-

dihydroisoquinoline having the following formula: ,7

COOCzHa- 5. 1 dicarbethoxymethylene 2 n propyll,2-dihydroisoquinoline having the fG11OWiIlg-f0 lmula:

C OOC2H5 c N I COOC2H5 (LHPCHPCHQ 6. A process for preparing a l-dicarbalkoxw' methylene-Z-alkyl-1,2 dihydroisoquino1ine comprising condensing, in the presence of a terti'ary organic amine which has an io-ni'zatiori constant greater than 10- at 25 C., an ester of malonic acid selected from those having the following general formula:

V COOR:

wherein R1 and R2 each represents an alkyl group, with a 1-alkyl-mercaptoisoquinoline alkyl quaternary salt selected from those having the following general formula:

wherein R and R3 each represents an alkyl group and X represents an anion.

'7. A process for preparing a l-dicarbalkoxyzmethyIene-Z-alkyl-1,2-dihydroisoquinoline comprising condensing, in the presence of a tertiary organic amine which has an ionization constant greater than at 25 0., an ester of malonic 8 acid selected from those having the followi'ng general formula:

COOR1 COOR:

wherein R1 and R2 each represents a primary alkyl group of the formula CnH2n+1 wherein n represents a positive integer of from 1 to 4, with a -1 alkylmercaptoisoquinoline alkyl quaternary salt' selected from those having the following general formula:

wherein R and R3 each represents a primary alkyl group of the formula CnH2n+1 wherein n represents a positive integer of from 1 to 4, and X represents an anion.

8. A process for preparing a l-diczirbalkoxymethylene-Z-alkyl-1,2-dihydroisoquinoline comprising condensing, in the presence of a trialkylamine which has an ionization constant greater than 10 at 25 C., an ester of malonic acid selected from those having the following general formula:.

COOR! wherein R1 and R2 each represents a primary alkyl group of the formula CnH2n+1 wherein n represents a positive integer of from 1 to 4, with a 1-alky1mercaptoisoquinoline alkyl quaternary salt selected from those having the following general formula:

wherein R1 and R2 each represents a primary alkyl group of the formula CnHZn-l-l wherein n representsa positive integer of from 1 'to 4, with a l-alkylmerca-ptoisoqumoline alkyl quaternary salt selected from those having the following general formula:

R/ x whereinR and R3 each represents a primary alkyl group of the formula CnH2n+l wherein n represents a positive integer of from 1 to 4, and X represents an anion.

10. A". process for preparing l dicarbethoxymethylene 2 methyl-1,2 dihydroisoquinoline comprising condensing in ethyl alcohol, in the presence of triethylamine, diethyl 'malonate with 1-meth y'lthioisoquinoline metho p toluenesulfonate.

11. A process for preparing l-dicarbethoxymethylene-2 ethyl-1,2-dihydroisoquinoline comprislngcondensing in ethyl alcohol, in the presence of triethylamine, diethyl malonate with 1- methylthioisoquinoline etho-p-toluenesulfonate.

12. A process for preparing l-dicarbethoxyethylene-2 ,-'j'n propy1-1,2-dihydroisoquinoline com- 10 prising condensing in ethyl alcohol, in the presence of triethylamine, diethyl malonate with 1- methylthioisoquinoline n-propo p toluene sulfonate.

FRANK L. WHITE. LESLIE G. S. BROOKER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS OTHER REFERENCES Mills et al., J. Chem. Soc. (London), vol. 121,

- page 2725 (1922).

Certificate of Correction Patent No. 2,518,512 August 15, 1950 FRANK L. WHITE ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 1, line 39, for that portion of the formula reading C000 read (700R? line 56, for that portion of the formula reading SR read .-S'R

and that the said Letters Patent should be read as corrected above, so that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 21st day of November, A. D. 1950.

THOMASgF-T MURPHY,

Assistant C'Ommissz'oner of Patents. 

1. THE 1-DICARBALKOXYMETHYLENE-2-ALKYL-1,2DIHYDROISOQUINOLINES WHICH ARE REPRESENTED BY THE FOLLOWING GENERAL FORMULA:
 6. A PROCESS FOR PREPARING A 1-DICARBALKOXYMETHYLENE-2-ALKYL-1,2-DIHYDROISOQUINOLINE COMPRISING CONDENSING, IN THE PRESENCE OF A TERTIARY ORGANIC AMINE WHICH HAS AN IONIZATION CONSTANT GREATER THAN 10**-5 AT 25*C., AN ESTER OF MALONIC ACID SELECTED FROM THOSE HAVING THE FOLLOWING GENERAL FORMULA: 